The specific goals of this research are to evaluate the effectiveness of triorganotin pyrethroid compounds as potential insecticides against larvae and adults of vector mosquitoes as well as to develop structure-activity relationship(s) between a parameter or parameters of the molecule and their toxicity. One species of mosquitoes to be used is in the genus Anopheles that includes vectors of human malaria parasites. A second species to be studied is Aedes aegypti, the primary vector of dengue and yellow fever. The third species of mosquitoes to be investigated are members of the Culex pipiens group that are responsible for the transmission of West Nile virus. The development of a new class of effective insecticides would be of tremendous value in the effort to reduce the spread of these highly debilitating and sometimes deadly diseases. Triorganotin compounds could potentially overcome problems such as resistance, commonly found with other insecticides. In addition, triorganotins are known to biodegrade to a non-toxic species, SnC14, in the environment. To accomplish these goals, triorganotin pyrethroid compounds will be synthesized and screened for their effectiveness against mosquito larvae and adult female mosquitoes. Initial studies will involve incorporating a triorganotin moiety into fragments of pyrethrins or those that mimic components of pyrethrin that have shown insecticidal activity. Long-term effects of the compounds will be evaluated using residual and delayed studies on the mosquito larvae. The insecticidal activity against adult mosquitoes on representative housing construction materials such as concrete, will also be evaluated. After evaluating the results of these studies, new triorganotin compounds will be designed and synthesized with the aim of developing more effective compounds. To reduce the number of compounds that must be synthesized and tested, quantitative structure-activity relationships (QSARs) between a physical parameter or parameters of the triorganotins and their toxicity will be developed.